Download the PDF, open the print dialog and choose Actual size or 100%. Select the same paper format and orientation as the PDF. In Acrobat, Actual size prints without scaling. Avoid Fit when the physical dimensions must stay unchanged.
Before you print
Use Actual size or 100% in the PDF print dialog. Match the paper format and disable any further resizing in the printer driver. The preview shows the PDF layout, not a guarantee of your printer’s printable area. Start with ordinary paper and measure before using photo paper.
The 20 mm scale check
The optional control square is 20 × 20 mm. It reserves space at the bottom of every sheet, so enabling it may add a page. Compare both measured sides with 20 mm. For example, a 19 mm side indicates 95% scaling. Do not enlarge the photo to conceal a scaling problem.
Find the cause
First compare the PDF paper format with the loaded paper. Next check scaling in the PDF viewer, then in the driver. If only the image edges disappear, inspect crop mode and borderless expansion. If only part of the sheet is missing, check the printer’s nonprintable margins.
Adobe Acrobat: How to print a PDF at 100%